PSAT Math Multiple-Choice Question 545: Answer and Explanation

Question: 545

In a stampede, a lion ran for 20 min, a cheetah ran for 10 min, an African wild dog ran for 10 min, and a zebra ran for 40 min. What is the total distance, in meters, that was covered by the animals?

• A. 80 m
• B. 102 m
• C. 80,000 m
• D. 102,000 m

Correct Answer: D

Explanation:

D

The question asks for the total distance in meters covered by four animals over specified periods of time given the distance they can cover in kilometers in 10 minutes of running. Use Bite-Sized Pieces and Process of Elimination to tackle this question. The distance covered by the cheetah and the African wild dog can be read directly from the table, since the table's data is based on an interval of 10 minutes. According to the table, the cheetah covers 18 km in 10 minutes, and the African wild dog covers 12 km in 10 minutes. Use proportions to determine the other two distances. Begin by setting up a proportion to calculate the distance covered by the lion in 20 minutes, being sure to match up units: . Cross-multiply to get 10x = 280, then divide both sides by 10 to get x = 28 km. Repeat the process to determine the distances for the zebra. The zebra ran for 40 minutes: . Cross-multiply to get 10x = 440, or x = 44 km. The total distance covered by the four animals in the specified time periods is 28 km + 18 km + 12 km + 44 km = 102 km. The question asks for an answer in meters, so set up a proportion to convert the units, being sure to match up units: . Cross-multiply to get x = 102,000 m. The correct answer is (D).